The Beaver Dam Eye Study cohort was first identified by a private census of the city of Beaver Dam, Wisconsin from September 15, 1987 to May 4, 1988, was examined from 1988-90 (baseline examination), and re-examined in 1993-95 and 1998-2000. The baseline examination formed the population for both cases and controls. Cases were defined as study participants who had died since the baseline examination from stroke or ischemic heart disease. Three participants per case were selected from the entire cohort at baseline as controls, age and sex matched to cases, irrespective of vital status. No participants were recruited specifically for this study.